The present invention relates to the rolling and unrolling of sheet material for such uses as solar screens and awnings, image (e.g., video and movie) projection screens, blackout screens, and insect blocking screens and more particularly, to a roller tube assembly including a spring biased roller tube slide and integral support cradle for a roll-fed sheet material.
Conventional roller tube systems make use of flexible sheet materials supported by elongated roller tubes. The roller tube, typically made from aluminum or steel, is rotatably supported and provides support for the flexible sheet material on the roller tube. Roller tube systems include manual and motorized systems. Manual roller tube systems have spring or gear driven roller tubes. Motorized roller tube systems have drive motors engaging the roller tube to rotatingly drive the tube. The drive motors for motorized roller tube systems include externally mounted motors engaging an end of the roller tube and internal motors that are received within an interior defined by the tube.
Conventional roller tube systems have support systems that engage the opposite ends of the roller tube to provide the rotatable support that is required for winding and unwinding of the flexible sheet material. The support system includes a drive end support assembly having a coupler engaging the open end of the tube for rotation. The coupler is adapted to receive the drive shaft of a motor such that rotation of the drive shaft is transferred to the coupler for rotation of the tube. The motor is secured to a bracket for attachment of the roller tube system to the wall or ceiling of a structure, for example. A coupler engaging an opposite end of the roller tube could receive a motor drive shaft or, alternatively, could receive a rotatably supported shaft of an idler assembly.
A roller tube supported in a conventional manner from the opposite ends will deflect in response to transverse loading, from the weight of an attached sheet material, for example. The response of a roller tube, supported at its ends in a conventional manner, from the weight of a flexible sheet material as well as from self-weight of the tube, results in a downward “sagging” deflection in a central portion of the roller tube with respect to the supported ends.
For roller tubes used with wider sheet materials (e.g., widths of 10 to 30 feet or more), support of the correspondingly long roller tubes in a conventional manner can result in sagging deflection detrimental to the appearance of a supported sheet material. V-shaped wrinkles, also known as “smiles”, can be formed in an unrolled sheet material supported by a sagging roller tube. Sagging deflection in a conventionally supported roller tube can also have a detrimental effect on operation. Moreover, any deflection in the roller tube can cause permanent damage to the sheet material (e.g. fabric, vinyl, polyester, acrylic, fiberglass). Video projection screen material is particularly prone to damage reducing visibility and performance over time.
During winding and/or unwinding of a sheet material, the sheet material is drawn onto the tube in a direction that is substantially perpendicular to the axis of the tube. Due to curvature along the length of a sagging tube, opposite end portions of a supported roller tube system will tend to track towards the center portion of the tube as the sheet material is rolled onto the tube. Such uneven tracking can cause the opposite end portions of the sheet material to be wound more tightly onto the end portions of the roller tube than the central portion of the roller tube. As a result, the central portion of the sheet material is not pulled tightly to the tube causing it to tend to buckle. This buckling of the central portion of the sheet material, if severe enough, can create variations in radial dimensions of the rolled sheet material along the length of the tube, thereby impairing subsequent rolling of lower portions of the sheet material. Uneven tracking can also cause surface discontinuities, known as “golf balling,” that include a permanent sagging pocket shaped discontinuity in the sheet material. After each revolution of the roller tube, as the material winds up on the tube, the imperfections (e.g., wrinkles) in the material, and particularly in the center thereof, will worsen.
The problem of sagging deflection in longer roller tubes has been addressed in prior art roller tube systems by increasing the diameter of the roller tube. Although increasing the roller tube diameter serves to reduce sagging deflection in conventional end-supported tubes, there are undesirable consequences associated with such a solution. Increasing the diameter of the roller tube increases weight, thereby potentially affecting the size and type of structure capable of providing rotatable support for the tube. Also, additional space required by the larger diameter roller tube and its associated support structure may not be readily available in many installations. Even if space is available, the bulky nature of the system due to the required large roller tube diameter is often objectionable for aesthetic reasons.
Other prior art attempts at preventing sagging involve the use of center supports and/or elongate support rollers in a variety of configurations located below the rotational axis of the roller tube. The elongate support rollers add weight and complexity to the roller tube system. The increased costs and failure mechanisms inherent in the more complex support systems diminish the advantages provided.
It has also been discovered by the present inventor that when the roller tube includes a drive motor within one end thereof, the sheet material (e.g., fabric) tends to wind tighter on the motor side of the roller tube. It is very important, however, that the material wind up evenly across the whole roller tube. A weight bar is provided at the leading edge of the material that unwinds from the tube. One indication that the material is winding evenly is that the weight bar remains parallel with the roller tube.
It would be advantageous to provide apparatus to ensure that roller tube sagging is prevented without the added costs and complexity of the prior art systems. It would be further advantageous to provide apparatus to ensure that the sheet material rolls up evenly on the roller tube, even when there is a motor within one end of the roller tube. It would be still further advantageous to provide a sliding mount arrangement for the ends of the roller tube, to allow the exterior surface of the material on the roller tube to remain in contact with a support cradle that supports the roller tube, all during the time that material is unwound from (and rewound on) the roller tube. The present invention provides the aforementioned and other advantages.